During the past year, the VRC's Vector Core created and tested new vaccine proteins and vectors expressing novel forms of envelope proteins, including fusion proteins. In addition, work continued to test different methods and routes of administration as well as prime/boost combinations to further optimize HIV vaccine strategies. Proteins with different adjuvants, VLP, nanoparticles and other vectors were tested. Several candidate vaccines that elicited promising immunogenicity data in preliminary studies are being tested further. Studies to understand development of broadly neutralizing antibodies using different knock-in mice are ongoing. These studies are testing novel immunogens designed to engage the CD4 and MPER binding site bnAbs. Epitopes recognized by vectors expressing neutralizing antibodies were also analyzed and tested for their ability to induce similar types of antibodies, in vivo.